The present invention relates to an exhaust silencer for an internal combustion engine, in particular a 2-stroke cycle engine and, more particularly, to an improvement in the construction of a spark arrester which is attached to the tail pipe of an exhaust silencer and which prevents exhaust sparks from being emitted from the silencer.
Japanese Utility Model Publication Nos. 3-50254 and 3-50255 disclose exhaust silencers having spark arresters.
More specifically, the exhaust silencer disclosed in Japanese Utility Model Publication No. 3-50254 has, as shown in FIG. 6 of the present application, a spark arrester c comprising a wire mesh screen a and a pipe b. The spark arrester c is attached to a tail pipe d of the exhaust silencer by means of a screw e extending laterally through the wall of the tail pipe d. Referring now to FIG. 7 of this application, the exhaust silencer disclosed in Japanese Utility Model Publication No. 3-50255 has a spark arrester g inserted into an exhaust pipe f. A sleeve-like member h is elastically fitted over the outer surface of the exhaust pipe f so that the spark arrester g is elastically retained in the exhaust pipe f.
The spark arrester c shown in FIG. 6 is disadvantageous in that it is not easy to set or remove the screw e through the exhaust opening in the direction perpendicular to the axis of the tail pipe d, although insertion and withdrawal of the spark arrester c can be done without difficulty. The known spark arrester of the type shown in FIG. 7 also is disadvantageous in that the construction is complicated due to the use of the sleeve-like member adapted to be fitted over the outer surface of the exhaust pipe h and high degree of dimensional precision is required to realize a tight fit between the spark arrester g and the exhaust pipe f. In addition, stick tends to occur due to corrosion between the sleeve-like member h and the exhaust pipe f and between the spark arrester g and the exhaust pipe f, making it difficult to detach the spark arrester g from the exhaust pipe f. In addition, the described support structure for supporting the spark arrester of the type shown in FIG. 7 cannot provide stable and constant force required for retaining the spark arrester in the exhaust pipe.